1. Field of the Invention
This invention relates to machine tools, and particularly but not exclusively to abrasive belt machines for polishing blades for rotodynamic compressors and turbines.
2. Description of the Prior Art
Machines for finishing turbine blades and the like by polishing with an abrasive belt have already been disclosed, for example, in U.S. Pat. No. 2,606,406 to P.M. Mueller. Mueller's patent discloses a machine which embodies a copying prinicple to ensure that the blade is polished to the correct shape; however, unless manual adjustments were to be made, the blades produced by this machine would become steadily larger as the belt became thinner through wear.
Copying grinding machines which avoid this disadvantage have been proposed in, for example, U.S. Pat. No. 2,641,089 to Fouquet. However, all such machines employ grinding wheels rather than abrasive belts, and avoid the need for manual adjustments only at the expense of dressing the grinding wheel at frequent intervals, for example after polishing a single blade. This is an uneconomical solution, and is in any case unsuited to a machine using an abrasive belt.